Battery charging apparatus



Fea. 17y 1948. M. L. PUGH 2,435,057

BATTERY CHARGING APPARATUS Filed Sept. 5, 1945 R1 oNmTlpNM la@ j] INVEN TOR. Ma/Zal i fag/, BY

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Patented Feb. 17,1948

UNITED STATES PATENT OFFICE BATTERY CHARGIN G APPARATUS Merlin L. Pugh, Minneapolis, Minn. Application September 5, 1945, Serial No. 614,465 7 Claims. (Cl. S20-20) The present invention relates to an apparatus for charging storage batteries at a high rate and in accordance with the condition of the battery. In my co-pending application, Serial No. 603,454, filed yJuly 6, 1945, for Battery charging apparatus, which has since matured as Patent No. 2,431,707, patented December 2, 1947, there is provided an apparatus which may be electrically connected to a storage battery while it is in an automobile or the like, and theapparatus adjusted fordetermining the condition of thebattery while simultaneously adjusting a time switch which will effect charging of the battery for a time period compatible with .the tested reading for `the battery when a charging control .switch is subsequently adjusted for charging the battery at a predetermined high rate. In the aforesaid co-pending application, the charging control switch is adjusted byobserving the recommended or desired current conditions at which the particular battery should be charged, and the charging control switch is moved until the correct amperage is'supplied as shown on an ammeter connected inthecharging circuit. If variations occur in charging current, it is necessary to readjust the charging control switch until the desired amperage is ragain supplied, .as indicated by reading the amm'eter. This, obviously, requires additional time and efforton the part of the user and involves the reading, interpretation and adjustment of the ammeter readings.

One object of the present invention is to providecomplete vautomatic control of the charging rate after the user'has set the charging control switch to the desired value.

Another object of the invention is to eleminate one meter from the prior charging apparatus, that gis, the ammeter, vtogether with thenecessity of the user observing the readings thereon .and makngfurther adjustments of the charging rate.

A further objectof the invention is to provide an automatic charging rate transformer .inthe charging circuit of a high speed battery charger in lwhich the user kmay quickly test the battery, determine the time and charging current required, and then manually set the time and charging current tothe determined values,.aiter which these factors vare automatically controlled.

Stillanotherobject of the invention is to provideabattery charging apparatus wherein` complicated testing technique A is eliminated .and in placecf it a Ytime vswitch isadjusted until a batteljy condition indicator indicates .a predetermined point, and,-there after, the charge control switch may be adjustedfor the recommended charging rate, after which the charging rate is automatically maintained, ther entire testing and setting of the apparatus for charging a battery being thereby reduced `to the two operations of adjusting the time switch and the charge control switch.

With theseand other objects in view, my invention consists in the construction, arrange,- ment and combination *ofl the Various parts of the device .whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in the claims, and illustrated in the accompanying drawing, yin which:

Fig. 1 is an electro-diagrammatic View of the improved battery Charging apparatus; and

Eig. 2-is a `plan view ofthe control panel for the charging apparatus- Referring to the drawing, numeral IIlindicates apanel on which is mounted a `batterycondition indicator, such as a voltmeter II A time switch I2 of a knowntype, having clock-actuated spring return mechanism, ka charge control switch I3 and a circuit breaker I4, varealso mounted on the panel I0. These devices maybe mounted on top of a suitable housing (notshown) in which an automatic charging rate-transformer I5, hereinafter described in detail, a rectifier I6, a fan I'I, a vload coil I8 and a relayv comprising a relay coil I9 and aload switchZIl aremounted These latter elements are shown in Fig. f1.

`As valso shown in Fig. 1, the transformer I5 has a primary coil 2I and a secondary coil 22. The 'primary coilfv2I isadapted to be energized from a source of 11G-volt A. C. current, for example, supplied -to terminals 23 and 24 and through power leads A25 and-zrespectively. The ian I'I is also energized from lthe terminals 23 andr24 through conductors 21 and/28, the transformer I5 vand fan Il being under control of a master switch 29. The jfan YI'I isrso locatedas to dissipate yheat Afrom the rectier I6 yand the load coil I8 asindicatedby arrows @which load coil may carry a current .of -from 150 to 175 amperes fromastorage battery k30 which is being testedand charged,

The battery 30 is, for example, the `storage battery of anautomobile and itis connected to the secondarycircuit `by a pair of heavy spring clips 3| and 32. Thecircuit breaker I4 automatically trips outif Athe clips 3| and `32 are connectedin wrong polarity relationship to theterminalsof vthe battery30or if aheavy loverload occurs ,while charging. f

. The voltmeter II-is connected-.across itheclips 3| and132 witharesistor '33 in series with the voltmeter to depress the zero reading thereof. Shunting the resistor 33 are resistors 34 and 35 in series with each other. The resistor 35 is part of a rheostat. the `movable blade of which is indicated at 36. The blade is mounted on a shaft 31, which shaft extends through and is connected with the timing mechanism of the time switch I2 for'settlng it. The shaft 31 has a cam 38 connected thereto, provided with a notch 39 for permittingv a relay'l switch 40 and the master switch 29 toY remain in the open position shown in Fig. 1, and to return to open position after the time switch I2 has been set and returns to the or Oi position. The time switch II may be provided with minutes of time indicia, if desired, although this is unnecessary except as a means to indicate how long the time switch will run after being set. When the time switch is in the "0" position, the rheostat 34-36 is at that time in its maximum resistance position.

A second relay switch 4I is in series with the relay switch* 4I)v and these two switches are in series with the relay coil I9, the three being connected across the clips 3I and 32. When the relay coil I9 is energized, it closes the load switch 28.

The apparatus just described is described and rotated. An insulated shaft 66 connects the con tact arm 51 with a second contact arm 6I associated with the resistance 53 and the two arms, 'l

therefore, move together, One side of the arm 6I is connected to the battery terminal 32'l through conductor 5I and the other side of the arm contacts terminals 62 corresponding to the terminals on the charge control switch I3 with resistances 63 in series between the terminals 62 and connected to direct current coil 46y position, thus breaking the circuit from the D. C.

claimed in the aforesaid pending application,

Serial No. 603,454, and in accordance with the present invention, the automatic charging rate transformer I5 is combined with the battery charger to automatically control the rate of charging 'a batteryvafter the user sets the rate of charge, and to` eliminate the need for an ammeter in the battery charger.

The transformer I5includes a core having end legs 42 connected by-primary, secondary, and direct current legs 43, 44' and.45, respectively. This transformer is described and claimed in my Patent No. 2,235,330, issued March 18, 1941, for Batter-ycharger.

The legs 43and 44 may be arranged double or in a plurality of other arrangements, but as to the legs 45, two of necessity arev provided. On the legs 45, direct current coils 46 and 41 are provided and? the coils are connected in series by a conductor 48. On the primary legs 43 of the transformer the primary coil 2I is wound. On the secondary legs 44, the secondary coil 22 is wound. Alternating current is supplied to the primary coll 2| from the terminals 23-24, as explained hereinbefore. Output from the secondary coil 2| is-conveyed to the rectier I6 through conductors 49Yand 50, whereby'rectified current -issupplied to the battery for charging it. With the Vexception of the direct current coils 46 and 41, a. standard transformer has thus far been described, without regulation. The direct current coils 46 and 41 provide automatic regulation. For this purpose, a pair of conductors 5I and 52 connect the -coils 46 and 41 across the battery, the conductor 5I connecting the coil 46 to the battery through a variable resistance 53 for a purpose hereinafter'described. A conductor 54 connects -a center tapy on the secondary coil 22 to the battery clip 3|-, and'conductor 52 is connected to conductor 54 at 55.

The charge control switch I3 is'provided with several positions marked-for convenience VOli 25, 50, '15 and 100 amperes. A terminal is provided at each of these points which terminalsA are connected to suitable taps 56 on the primary coil 2'I of thev transformer. A movable contact arm 51 has one side -thereof connected to one side; ofthe mainswitch 29 `by conductor 5 8 land makes contact. wlththe `desired terminal as it is coils46 and 41 to the battery 39.

' Operation In the operation of the battery charging apparatus, when the parts are in the position shown in Fig. 1, that is, with the time switch I2 set at 0" or Off and the charge control switch at the Off position, the clips 3I and 32 may be connected to the terminals of a storage battery 3u and the voltmeter will give a reading which has no particularsignicance. In order to test the battery, it is necessary to test its voltage with a load applied thereto.

The operator then rotates the time switch I2 from the 0 position which causes the cam 38 to close the switches 29 and 40 and reduce the resistance in the resistor 35. Closure of the master switch 29 causes the fan I1 to'operate (for subsequently dissipating heat from the rectifier I6v and load coil I8) and supplies current to the charging switch blade 51 through conductor 58, Closure of the switch 40 energizes the relay coil I9 through conductors 65 and 66 thereby closing switch 20 to throw the load coil I8 across the terminals of the battery 30. This will cause an indicating needle 61 to drop to a lower reading, because the battery is discharging, and accordingly a true test of the battery can now be made on the voltmeter. If the battery is partially discharged, the needle will fall below checkv line 68. If the pointer is above the check line 68, it shows the battery is fully charged.

The timer switch I2 is now adjusted further clockwise which causes the resistance 35 to be gradually reduced and this increases the flow of current through the voltmeter II so that the needle 61 swings further toward the right. When it reaches the check line 68, this indicates to the operatorthat the time switch I2 has been properly adjted.

If it is impossible for the operator to bring the needle up to the check line 68, even after rotating the knob 3 6 to the extreme clockwise position, it indicates that the battery is in a ques` tionable state and should be given a five-minute trial charge at amperes and re-tested again in the above manner. If, after a trial charge, the operator is still unable to bring the needle 61 up to check line 68, the battery may be considered defective and should be discarded.

The next step in the operation is to adjust theI charge control switch I3 by rotating the arm 51 to one of the marked positions.

the relay switch 4I to effect deenergization of theV relay coil I9 and opening switch 20 to break thex e This causes thev arm to leave the spring blade 64, thereby opening* Ine-movement ef the aan s1 -cfthecharge control-switch IS-also moves-arm 151| ofthe variable resi'stor`53 to one of its positions in 'which 'more `tir less resistance i's'n the circuitto the D.' C'. coils 4S, 41 ofthe transformer I5. The -pri'ma'ry'lil of 'the 'transformer 'I 5 is'falso inthe circuit fat a value ydetermined -by the arm 51and terminals ofthe charge control switch I3. Charging of the battery will continue for the proper time, rdepending von the setting of the time switch I2,.a's-a1rea`dyfde scribed.

Furthermore, the charging rate will b'e-'mainftained constant because the taps 56 on'tlie'primary' coil 2I will give anapproximately vconstant Vformer will maintain the' set. rate constant in the following manner, it being understood that 'the resistances 63 will Apermit more orless currentto -fi'o'w-to the coils 46 .and 41 depending 'on' the setting of arm 6I as ydetermined by. the setting-of arm 51 vand the `taps in use on the primary coil 2l of the transformer. Once the value is set for charging however, it will not vary as the battery becomes more fully charged and the resistance to current ilow therethrough increases (the charging voltage remaining constant).

The connection of the direct current coils 4B and 41` in series and in opposition causes the re;- sultant-of the alternating current voltage-built up in each coil to buck each other Aand the current at leads `5I and 52, is, therefore, Qzero. Connecting these leads across the battery 3l! results inthe current from the battery' energizing the coils 4 6 and 41 in proportion to the strength of the battery.

The direct current in the coils 46 and 41 causes a 5 direct current magnetic flux in the legs 45 of the transformer. This reduces the number of alternating current flux lines in the legs 45 and forces them into the legs 44, thereby increasing or decreasing the secondary current from the secondary coil depending on the amount of current flowing in the coils 46 and 41. As a result, regardless of the condition of the battery 3U at various stages of the charging process, the rate of I charging will remain constant. It is obvious that at low charging rates more of the resistances S3 are in the circuit leading to the D. C. coils 46 and 41 and, therefore, the -current in the coils will be less and the charging rate lower, but constant, and in accordance with the taps 56 in use on the primary coil 2I of the transformer. As higher charging rates are desired, the resistances 63 are successively removed from the circuit and higher and constant charging rates result because of increased D. C, current in the coils 46 and 41, and because of the increased eifective positions of the primary coil 2 I After the charge control switch I3 has been adjusted from the Oli position, the relay circuit for the coil I9 is now open, thus opening the load circuit, and the voltmeter l I will now give a different reading because the resistances 34 and 35 are out of the circuit due to the opening of switch 4I and due to the battery now being charged rather than discharged. The needle 61 during charging should fall above the check line 68 and will gradually indicate a higher voltage by swinging toward the dark portion of the scale toward the right, the left end of this portion indicating about 8 volts. If the voltage then rapidly rises in this portion of the charging zone, it indicates full charge.

From the foregoing description, it will be obvious that I have provided a battery charging apparatus wherein the matter of setting the charger rrproper time of'charging 'is reduced tov a single operation and wherein the rate of charge when set :remains constant 'without adjustment for the necessity. for the operator to watch anammeter. Thus, Viorfa battery that may be charged at a high rate, `there are only three operations neces.- sary, namely: (1) placing the: clips 3Iand 32 on the battery, (2) rotating fthe'arm 36 of the time control switch I2 until need-le `61 of voltmeterl Il reaches the lin'eii; and (3) 'adjusting the charge control switch I3.

Some changes may be made in the construction and arrangement of the parts of my device without departin'gfrom the real spirit and purpose of my invention, and it is my intention to cover by my claims any vmodiiied forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

AI claim as my invention:

V1. vIn battery charging apparatus, a charging circuit including a time switch for determining the time-*a battery is to be charged, a transformer including a kprimary coil, a secondary coil, a 'plurality of 'taps on the primary coil for varying the output of the secondary coil and a pair of yopposed and serially connected `direct current coils connected Vacross `the b'attery,1a variable resistor connected between the battery and the direct current 'coils and a charging switch for determining the rate of charge during said time and being adjustable to simult-aneously'change the tap setting of the primary coil and the resistance of the variable resistor to set and maintain Vconstant. the output ofthe transformer to the battery. Y

2. In a battery charging apparatus, a charging circuit including a time switch for determining the time a battery is to be charged, a transformer including a primary coil, a secondary coil, a plurality of taps on the primary coll for varying the output of the secondary coil and a pair of opposed and serially connected direct current coils connected across the battery, a variable resistor connected between the battery and direct current coils, and a charging switch for setting the rate of charge during said time and adjustable t0 vary the resistance of the variable resistor to maintain constant the output of the battery transformer.

3. In battery charging apparatus, a charging circuit including a time switch, a meter connected with the battery for indicating the voltage thereof, a variable rheostat in circuit with said meter and mechanically connected with said time switch for simultaneous operation therewith to indicate the proper time period for charging the battery in accordance with a predetermined reading on the meter. and a transformer in the charging circuit including means for maintaining said charging rate constant during said time.

4. In battery charging apparatus, a charging circuit including a time switch, a meter connected with the battery for indicating the voltage thereof, a variable rheostat in circuit with said meter and mechanically connected with said time switch for simultaneous operation therewith to indicate the proper time period for charging the battery in accordance with a predetermined reading on the meter, a transformer in the charging circuit including means for maintaining said charging rate constant durlng said time, and an adjustable switch for manually varying the output of said transformer.

5. In battery charging apparatus, a charging circuit including a -time switch for .controlling saidcircuit, a transformer including means for maintaining the charging rate constant, a charge control switch for adjusting the output of said transformer to obtain a desired constant: out;- put value, a rheostatvariable in accordance with ,the setting of said time switch, a meter for the battery in circuit; with said rheostat, switching means for controlling the charging of the battery and the circuitjithrough said rheostat operated by said charging controlr switch, and a load for the battery adapted to be placed in circuit with said meterv only atea time when the battery is not being charged, said switching means eiecting removal of the load from the battery when it is adjusted for charging the battely. 1 i

6. A battery charging apparatus comprising a charging circuit, a normally open master switch for controlling said circuit, a time switch movable to a plurality of positions including an Off position, said time switch in said Off position opening :said master switch, ,and in all other positions closing said master switch, a load for said battery, a Voltmeter for testing the battery while said load is applied thereto, arheostat for modifying the indication on said voltmeter in accordance, with the position of said time switch, a transformer including means for automatically maintaining a constant charging rate, and av charge .control switch for disconnecting said load from the battery when it is moved to the charging position and for selecting a desired constant charging rate from said transformer.

k'l'. Battery testing and charging apparatusfor high-,rate battery charging comprising a meter circuit adapted to bevconnected tovterminals provided von the battery, a battery` load circuit adapted to be connected to said Vbattery termi'- -nals, a fixed load forl said battery ,circuit means -for connecting said-load into said battery load circuit during testing, a chargingcircuit, a time switch in the charging circuit containing time indicia thereon, a voltmeter connected in said meter circuit, said vcltmeter including indicia for visually determining in timev units, in con- `iunction with said-time indiciaqon said time switch, the amount of time required to substantially fully charge the battery, without the necessityv of any calculations, a charging switch for determining the rate of charge, and a charging transformer in said charging circuit, said charging transformer including means4 for maintaining said charging rate constant.

. MERLIN L. PUGH.

REFERENCES CITED V'Iheiollowing references are of record in the le of this patent:

UNITED STATES PATENTS 

